July 2008

Propagation Forecast

The second half of June will have seen 2 minor disturbances. On the 19th and 20th. The A index was at 10 and the K at 3, returning to ‘normal’ by the 21st with the A index at 5 and the K index at 2, until the 25th to the 27th with the A index peaking at 10 on the 26th. ‘Normal ‘ conditions will prevail until July 3rd to the 5th, with the A index again peaking at 10 on the 4th July. Things will remain ‘normal until 11th July with another disturbance until at least the 14th, the worst day being the 12th, with the A index peaking at 15 and the K index at 4.
Sunspots and Global Warming

The Spórer minimum (1420-1570) The Maunder minimum (1745-1615), and the Dalton Minimum (1790 to 1830) have coincided with a time when Earth’s climate was colder than average. The correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.

Like the subsequent Maunder Minimum, the Spörer Minimum coincided with a time when Earth's climate was colder than average. This correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.

Here is an interesting article in the Belfast Telegraph by Dr David Whitehouse (12 May 2007):
Can the Sun Save Us from Global Warming? (Low Sunspot Activity)
"Something is happening to our Sun. It has to do with sunspots, or rather the activity cycle their coming and going signifies. After a period of exceptionally high activity in the 20th century, our Sun has suddenly gone exceptionally quiet. Months have passed with no spots visible on its disc.
We are at the end of one cycle of activity and astronomers are waiting for the sunspots to return and mark the start of the next, the so-called cycle 24. They have been waiting for a while now with no sign it's on its way any time soon.
Sunspots – dark magnetic blotches on the Sun's surface – come and go in a roughly 11-year cycle of activity first noticed in 1843. It's related to the motion of super-hot, electrically charged gas inside the Sun – a kind of internal conveyor belt where vast sub-surface rivers of gas take 40 years to circulate from the equator to the poles and back. Somehow, in a way not very well understood, this circulation produces the sunspot cycle in which every 11 years there is a sunspot maximum followed by a minimum. But recently the Sun's internal circulation has been failing. In May 2006 this conveyor belt had slowed to a crawl – a record low. Nasa scientist David Hathaway said: "It's off the bottom of the charts... this has important repercussions for future solar activity." What's more, it's not the only indicator that the Sun is up to something.
Astronomers called it the "Maunder Minimum." It was an astonishing discovery: our Sun can change. Between 1645 and 1715 sunspots were rare. About 50 were observed; there should have been 50,000.
Ever since the sunspot cycle was discovered, researchers have looked for its rhythm superimposed on the Earth's climate. In some cases it's there but usually at low levels. But there was something strange about the time when the sunspots disappeared that left scientists to ponder if the sun's unusual behaviour could have something to do with the fact that the 17th century was also a time when the Earth's northern hemisphere chilled with devastating consequences."

THE SUN'S CHILLY IMPACT ON EARTH
A new NASA computer climate model reinforces the long-standing theory that low solar activity could have changed the atmospheric circulation in the Northern Hemisphere from the 1400s to the 1700s and triggered a "Little Ice Age" in several regions including North America and Europe. Changes in the sun's energy was one of the biggest factors influencing climate change during this period, but have since been superceded by greenhouse gases due to the industrial revolution. (NASA News).
(Thanks to Ken Fletcher and Mike Terry for regular updates). Links to the full articles are on my website. http://www.jameswelsh.org.uk